The Caribbean, Central and South America network for HIV epidemiology (CCASAnet) brings together the clinical and data expertise and resources of Vanderbilt University and clinical sites in Argentina, Brazil, Chile, Haiti, Honduras, and Peru. CCASAnet will use state-of-the-art technologies to create a shared data repository and associated methods for data merging that forms the union of existing HIV-related clinical data sets available at the participating sites. The project will conduct and facilitate research using the shared data repository that enables answers to questions that cannot be answered by any single source, and develop and evaluate new biostatistical methods relevant to HIV epidemiology. CCASAnet will develop and conduct a program of face-to-face and educational and training based on International Good Clinical Practice standards that will assist sites to improve the quality and consistency of their clinical research activities. The CCASAnet Coodinating Center will provide an infrastructure for review and approval of data use requests, create end-user data access tools that facilitate research using the shared data repository, and assist investigators with analysis and publication of research findings. CCASAnet will also participate with other regional IEDEA networks in the development of international standards for sharing and meta-analysis ofHIV- related data. By these activities, CCASAnet will help advance both the science of HIV epidemiology, and the information science that underpins international research collaboration.